Containers with connection fittings are known from, for example, WO 2008/083782 A2, DE 101 38 365 A1, and DE 10 2006 034 638 A1.
Large-volume containers that hold more than 10 liters, and in particular 30 liters or 50 liters, are generally used to store a liquid, such as beer, and to dispense that liquid under pressure. Among these are special large-volume containers called “kegs.” Kegs are typically returnable vessels that have been developed for the industrial filling and sterile storage of beverages.
As a rule, a keg has a valve on its top side. This valve is sometimes called a “keg head.” A suitable tap head can be mounted on the keg head. The tap head supplies a propellant gas from an external container into the keg. A suitable propellant gas is carbon dioxide or nitrogen. The propellant gas, once in the keg, generates an overpressure in the interior of the keg. This overpressure ensures that the liquid stored in the keg can be removed via a rising pipe and a tap dispenser. The tap head seals the container tightly such that the liquid stored therein remains sterile.
The overpressure created by the propellant gas in the keg permits beverage to be pushed out through the rising pipe from the interior of the keg upon opening a tap cock. Closing the tap cock closes the valve, which in turn closes the keg. In this state, the keg is airtight, and further storage of the content is possible. Closing the valve also prevents any residue from drying up and maintains overpressure in the keg.
Two problems arise in connection with kegs. The first relates to filling the keg, and the second relates to cleaning the connection fitting.
Usually, one fills a keg with the connection fitting already mounted in the neck. In most cases, the connection fitting has a fitting body and an abutment for a seal. When the connection fitting is in the container neck, the opening available for filling is much narrower. This results in turbulence as the liquid product flows into the container. Depending on the character of the liquid product, such turbulence can lead to foam formation. To avoid excess foaming, one must reduce flow rate. Reducing flow rate, however, reduces filling speed.
Known connection fittings are closed when they are delivered to a bottling plant. This makes them difficult to clean. In particular, there is a risk of dirt accumulation in the region of the closed sealing faces. This accumulated dirt only be removed, if at all, in a very expensive manner.